Renal function in hypercalcemic dogs during hydropenia and during saline infusion.

The effects of calcium-gluconate infusions on renal function were studied in unanesthetised dogs. Each dog was studied during hydropenia and saline infusion. Hypercalcemia, mean serum calcium 3.85 mmol/l (hydropenia) and 3.62 mmol/l (saline infusion), increased fractional excretion of sodium (CNa/CIn), calcium (CCa/CIn), and magnesium (CMg/CIn). The increase was significantly higher in saline-expanded dogs than in hydropenic dogs. Fractional excretion of potassium (CK/CIn) was increased in hydropenia but remained unchanged in saline-expanded animals. Fractional excretion of phosphate (Cp/CIn) was not consistently changed by hypercalcemia. Fractional excretion of chloride (CCl/CIn) was markedly increased in saline-expanded dogs but was not changed in hydropenia. Urine osmolality was reduced in hydropenic dogs but unchanged in saline-expanded dogs. In hydropenic as well as in saline-expanded dogs tubular reabsorption of solute-free water (TcH2O/CIn) increased during the first hour of hypercalcemia. In hydropenic dogs hypercalcemia caused a slight but significant decrease in blood pH, standard bicarbonate, and base excess. In hydropenic as well as in saline-expanded dogs glomerular filtration rate (CIn), renal plasma flow (CPAH), and filtration fraction were unaffected.